Headspace

[Mr.Snerdly]

If you seat a bullet in a empty case, make it longer than normal, close the bolt and then measure the overall length and then remove the bolt, drop the bullet in the chamber and drive the case forward (I use a phillips screwdriver in the primer pocket and tap lightly with a small plastic hammer) and again measure the overall length, will this give you the headspace? I come up with .003" Does that sound reasonable?

[Ted_Feasel]

If you seat a bullet in a empty case, make it longer than normal, close the bolt and then measure the overall length and then remove the bolt, drop the bullet in the chamber and drive the case forward (I use a phillips screwdriver in the primer pocket and tap lightly with a small plastic hammer) and again measure the overall length, will this give you the headspace? I come up with .003" Does that sound reasonable?The.saami tolerance is .003 I believe.. you can have anywhere. 001 to .003

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[mnbogboy2]

Headspace is a measurement from the bolt face to shoulder datum. The measurement you are trying to get is CBTO (cartridge base to ogive where the bullet first meets the lands of the rifling). Forcing the bullet into the lands as you suggest is of no value.
I suggest you research cartridge & rifle headspace as well as CBTO, they are completely two different things. Safety is a concern with both.

[celltech]

Could also use layers of scotch tape, or shim stock (I use pieces cut from feeler gauges) on an empty case to see how much wiggle room you have. Think the tape is generally .002" per piece.

[efm77]

In the grand scheme of things, headspace gauges aren't that expensive. I'd err on the side of caution and get a set of gauges (go, no go, and field) rather than trying to cheapen out using a brass case and tape, or one gauge and tape. I'd rather play it safe than take that kind of risk.

[Ted_Feasel]

I have a set of Clymers for all my rifle cals, i.would agree to use gages and don't mix and match as in dont use clymer go and forster no go.. PT, Clymer, Forster all make good gages, I just like to stick with one manufacturer for go/no.go , buy them as a set

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[celltech]

So while we are talking about it...what spacing do you aim for? I am setting mine to where the bolt will not quite close on the GO gauge. I used to do GO+.002-3" but changed my mind.

[sharpshooter]

Go gauge +.002". You don't want it below minimum.

[Mr.Snerdly]

Could also use layers of scotch tape, or shim stock (I use pieces cut from feeler gauges) on an empty case to see how much wiggle room you have. Think the tape is generally .002" per piece.


I would think a feeler gauge would be better than tape. I would hate to ruin a good feeler gauge but I guess you don't use .0015" very often. Shim stock would be better if you could find a small amount of it or a mechanic that might give you some, although I doubt .001", .0015" or .002" is very common.

[yobuck]

The military definition of headspace is, the distance measured from the face of the bolt to the face of the cartridge when the round is fully chambered.

[celltech]

Go gauge +.002". You don't want it below minimum.

Any reason why, other than to insure various ammo will fit? I am handloading and all my brass still chambers without resistance.

[mnbogboy2]

Any reason why, other than to insure various ammo will fit? I am handloading and all my brass still chambers without resistance.

I try to set as close to minimum as possible also but not less than the go. Ive had up to 4 rifles of the same caliber at one time within a half thou. All cut with the same reamer and all shared same die setting.
Usually i set "snug" and the torquing nut relieves about a thousandth or so. One "scotch" tape thickness becomes "tight" and will distort the tape. Two thicknesses is a no-go.
Layer the tape on the gauge and measure multiple thickness to be sure, it does vary.
If you do get it shorter than SAAMI most if not all brass will fit but some dies will not resize it without modifying the die or shell holder.

[mikeinco]

so , as was pointed out HEADSPACE is a characteristic of the chamber/boltface.
without a precision ground gauge you cannot MEASURE headspace.
hornady etc case measuring tools are not PRECISE, AND SELDOM the right dia,

you can set CLEARANCE so rounds chamber, cases get sized to fit.

and as was pointed out bullets have NOTHING to do with headspace.

i do subscribe to a go gauge and measured thin tape as a no go tool
i set my headspace at ZERO to maybe 1/2 thou. reset if it clears at .001
just me.

[Mr.Snerdly]

Another thing, these digital calipers can be off quite a bit. They measure to .0005". When do they round to .0005"? Is it when the actual measurement is .00025? Going the other way, when do they round to .0001'? is it at .00075? With an actual micrometer it is fairly easy to read .0001". Another thing, it is fairly difficult to get everything perfectly square in two directions with the small blades on each end. A micrometer has a much better base for getting everything squared as close to perfect as possible. I absolutely have to get some micrometers to do a little better job. Maybe very high end calipers measure to more precision than .0005" but I bet they would be a lot more expensive than a couple good used micrometers. It is also possible it doesn't make that much difference. Years ago the best racer on a couple local tracks said "If it ain't off more'n a half inch, it's close enough." Naturally, this has to be read with regard to the application. He was talking about the variation in wheelbase from one side to the other on their super modified.

[mikeinco]

digital calipers DISPLAY to .0005, but if you read the fine print they claim accuracy to 0.001....
not close enough for a gunsmith...
for a savage headspace adjustment at home, probably just fine.

if you set it at zero with a headspace gauge...not much to measure

check max with a pc of measured thin tape...
OHHH
and you cannot do this with the ejector in place


Another thing, these digital calipers can be off quite a bit. They measure to .0005". When do they round to .0005"? Is it when the actual measurement is .00025? Going the other way, when do they round to .0001'? is it at .00075? With an actual micrometer it is fairly easy to read .0001". Another thing, it is fairly difficult to get everything perfectly square in two directions with the small blades on each end. A micrometer has a much better base for getting everything squared as close to perfect as possible. I absolutely have to get some micrometers to do a little better job. Maybe very high end calipers measure to more precision than .0005" but I bet they would be a lot more expensive than a couple good used micrometers. It is also possible it doesn't make that much difference. Years ago the best racer on a couple local tracks said "If it ain't off more'n a half inch, it's close enough." Naturally, this has to be read with regard to the application. He was talking about the variation in wheelbase from one side to the other on their super modified.

[Fordoldfart]

I use gauges. I set so I can feel that when the bolt goes into battery it is snug against the gauge. That way the bolt will not even try to close on a no-go.
You want to Remember you are putting your face next to a chamber that’s going to have to with stand up to 60,000 psi of pressure.
To save approx. $60 - $65

[Tompuz]

For head space I use the "reference method". It's for reloading purposes. I take soma fired brass (3 times) and use redding instant indicator configured for datum lenght. The reference point is the redding brass delivered with instant indicator. I use the longest DL if brass have diffrent measurements. This should get me in 0.001" accuracy. If I need to take barrel out and in. I would remove ejector and use the 3x times fired brass as a gauge. Sadly, not an optimal method for rebarreling to a new barrel.

[sharpshooter]

The easiest and most precise way to measure the clearance is with plasti-gage.

[mikeinco]

are you talking headspace or head clearance, ?
and what are you using the plastigage on ??
( as in you still need a headspace gauge rigtht ??)


The easiest and most precise way to measure the clearance is with plasti-gage.

[Mr.Snerdly]

The easiest and most precise way to measure the clearance is with plasti-gage.

That sounds like a good idea. Cheap too.